My Running Dilema

I have not been able to run for almost two weeks now. I can feel the change in my body. It is getting soft again and my clothes are getting tight. With my running, if I don't do it, I lose it. I was able to run 2 miles on Friday - it felt like such a success! But it was also frustrating, because I got sick right after and couldn't run all weekend. Here is my dilema - do I push myself so I can run in the SL half, or do I admit I just can't do it and accept defeat? I don't think I am going to donate blood again for a while. It is too dangerous!